Embodiments of the present disclosure relate generally to enclosures, and more particularly to systems and methods for thermal management of enclosures.
Enclosures, such as electronic chassis typically include multiple electronic devices enclosed in a metal casing. The metal casing, in some applications, hermetically seals the electronic devices, thereby protecting the electronic devices from the external environment. Such protection is often desirable because the chassis may be employed in rugged environments where temperatures may fluctuate from very hot to very cold. During operation, the electronic devices within the chassis may generate heat. However, as the chassis is hermetically sealed, these electronic devices may be unable to dissipate the heat effectively, and thereby their temperature may further increase. Such high temperatures within the chassis may increase the temperature of the electronic devices beyond their maximum reliable operating temperature. If the heat is not extracted, the electronic devices may underperform, shutdown, or get damaged. Therefore, to extract the heat from within the chassis, most electronic chassis include thermal conductive paths that conduct the heat away from the electronic devices and transport the heat to the metal casing. Once the heat is conducted by the metal casing, various thermal management techniques may be utilized to dissipate heat from the metal casing.
Thermal management techniques may be broadly divided into two categories—passive cooling and active cooling. In passive cooling, natural air convection is utilized for cooling the chassis. In active cooling, an auxiliary device such as a fan, cooling plate, or heat exchanger is utilized for cooling the chassis. In one example of a passive cooling technique, surface extending fins may be arranged on an outer surface of the metal casing to increase the surface area of the enclosure. The increased surface area may aid in dissipating the heat at a faster rate as compared to casings without fins. Alternatively, an active cooling technique may be employed, where a fan may be disposed along one or more walls of the metal casing to increase the airflow around the metal casing such that greater amount of heat is dissipated per unit time as compared to natural convection cooling.
Passive cooling is generally effective for low power applications or applications that operate in low temperature environments, but is often insufficient for high power applications or applications that operate in high temperature environments. Active cooling, on the other hand, is more efficient in high power and high temperature applications as the active devices may be controlled to dissipate a desired amount of heat. Unfortunately, in ruggedized applications such as in vehicles, active cooling is often not a desirable solution. For example, fan cooling is generally not employed in vehicles because fans include multiple ball bearings. While in motion, vehicles may experience excessive vibrations, which may damage the ball bearings relatively quickly. In addition, the environment may include sand and/or dust, which may penetrate the fan bearings resulting in premature wear and failure. If the fan fails mid-operation because of such wear, electronic devices within the chassis may overheat and shutdown. Such a shutdown may lead to loss in communication, sensor control, and the like. Therefore, in ruggedized chassis, passive air-cooling is used for cooling even though these passive cooling systems may hinder the performance of the electronic devices within the chassis.